Type 1 scalpings softspot - Compacted layer of mot type 1 not stable
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Hi guys
hope you can help.
My son offered to extend the block paving shared with my neighbour in 2 areas, one for each household. The total area for both is 18 square metres.
My neighbour's side has gone well and he has extended the herringbone up to the new haunching. He will complete the darts and slips this weekend. Lovely job.
On our side there are 2 softspots in the scalping layer are compaction 3 times. One area, close to the haunching, I am not worried about since it will never be driven on. Hover, the other spot is just over a metre diameter still moves when I walk on it ( 19 stones, if that's important)
We are on heavy clay in this area but the scalpings are probably more than specified as the lad got carried away with the excavator. ( 1 extra 4 yard skip and then 2 extra tonnes of type 1 to backfill)
Can anyone suggest our options? Suggestions on weight reduction will fall on stoney ground.
hope you can help.
My son offered to extend the block paving shared with my neighbour in 2 areas, one for each household. The total area for both is 18 square metres.
My neighbour's side has gone well and he has extended the herringbone up to the new haunching. He will complete the darts and slips this weekend. Lovely job.
On our side there are 2 softspots in the scalping layer are compaction 3 times. One area, close to the haunching, I am not worried about since it will never be driven on. Hover, the other spot is just over a metre diameter still moves when I walk on it ( 19 stones, if that's important)
We are on heavy clay in this area but the scalpings are probably more than specified as the lad got carried away with the excavator. ( 1 extra 4 yard skip and then 2 extra tonnes of type 1 to backfill)
Can anyone suggest our options? Suggestions on weight reduction will fall on stoney ground.
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firstly, when you say scalpings, your not talking about road planings are you?
secondly, you say there is a good layer of them, but has it been compacted in a layer at a time, or was it all put down and then compacted?
it sounds like you might need to dig the soft spot out and add more hardcore.
I dare say that had terram been used, this problem could have been avoided
Not little slithers i hope?? ???
secondly, you say there is a good layer of them, but has it been compacted in a layer at a time, or was it all put down and then compacted?
it sounds like you might need to dig the soft spot out and add more hardcore.
I dare say that had terram been used, this problem could have been avoided
He will complete the darts and slips this weekend.
Not little slithers i hope?? ???
Dan the Crusher Man
01442 212315
www.crusherhire.co.uk
"a satisfied customer? we should have them stuffed!"
01442 212315
www.crusherhire.co.uk
"a satisfied customer? we should have them stuffed!"
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the main thing with any excavation for block paving or patio is to asses the sub grade i.e. the mud
if it is soft it must come out
if the ground is generally clay (as it is here in luton) we always use terram to stabilise the subbase
what kind of compaction are you using?
also darts and slips are a big no no
see this page for
info
i just did a load of cutting in today will get a picture tomorrow weather permitting
LLL
if it is soft it must come out
if the ground is generally clay (as it is here in luton) we always use terram to stabilise the subbase
what kind of compaction are you using?
also darts and slips are a big no no
see this page for
info
i just did a load of cutting in today will get a picture tomorrow weather permitting
LLL
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If a sub-base is moving when *anyone* walks over it, regardless of their weight, it's WRONG!
Excavate, put in a stabilisation membrane then re-construct the sub-base, in layers, as described here
Excavate, put in a stabilisation membrane then re-construct the sub-base, in layers, as described here
Site Agent - Pavingexpert
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Thanks guys
first I am not an expert so forgive me if I use the wrong term.
Clarifing some of the points made
I bought Type 1 scalpings according to the invoice from SEHMI
We did noy use a membrane which is often shown as optional.
The clay did not move when we finished excavating.
The scalpings when down in 3 layers compacting after each load.
We used a medium weight plate compactor.
We seemed to draw up the water during the compaction process.
When I said darts & slips only 2 are smaller than half a brick. This is unavoidable due to this is an extension to existing paving and the lie of the land.
The existing block paving has been down 22 years and did not have a membrane. It did have scalpings & sharp sand in the correct proportions but there are minor dips in a few areas.
Thanks for all the advice.
first I am not an expert so forgive me if I use the wrong term.
Clarifing some of the points made
I bought Type 1 scalpings according to the invoice from SEHMI
We did noy use a membrane which is often shown as optional.
The clay did not move when we finished excavating.
The scalpings when down in 3 layers compacting after each load.
We used a medium weight plate compactor.
We seemed to draw up the water during the compaction process.
When I said darts & slips only 2 are smaller than half a brick. This is unavoidable due to this is an extension to existing paving and the lie of the land.
The existing block paving has been down 22 years and did not have a membrane. It did have scalpings & sharp sand in the correct proportions but there are minor dips in a few areas.
Thanks for all the advice.
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without sounding pedantic, scalpings in quarrying terms is the material removed from blasted rock that is deemed of poor quality and can contain shite and clay. the term is also used in other crushing operations to remove the unvalued material. You'd have a scalping screen in before processing. anyone selling 'scalpings' i would guess would be poorer quality material and not really a proper type 1 unless it has been tested to prove it's compliance.
i used to love using tarmac, but got fed up with getting my asphalt
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im with big phil on this, scalping are the cheap crap left over, and type 1 scalpings is a bit of oxy moron.
Giles
Groundworks and Equestrian specialists, prestige new builds and sports pitches. High Peak, Cheshire, South Yorkshire area.
http://www.gbgroundworks.com
Groundworks and Equestrian specialists, prestige new builds and sports pitches. High Peak, Cheshire, South Yorkshire area.
http://www.gbgroundworks.com
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But it comes back to something I mentioned a few days ago: terminology. Look at how many people talk about 'cobbles' when they are actually referring to setts.
In some parts of England, notably that London and beyond, the term 'scalpings' is used to refer to almost any crushed stone. Given that Praesepe was sold "Type 1 Scalpings" I'd guess that it is genuine DTp1, otherwise why use the term "Type 1", but the BM has put scalpings rather than simply "stone". There is no such thing as Type scalpings - there is scalpings, and there is Type 1, but the two are sort of mutually exclusive.
The methodology outlines is OK except for one point - the use of a "medium weight plate compactor". I know this is something else I've rattled on about previously, but according the the BS, the *minimum* plate mass for compaction of sub-base material on a category IV pavement (a driveway or patio) is 80kg. The vast majority of contractors, and nearly all DIYers end up using a plate of maybe half that mass, which is why we see so much settlement on completed driveways.
Whenever possible, a vibrating roller should be used to compact the sub-base. If you're lucky enough to own or have access to an 80kg plate, all well and good, but even one of the most popular plates, the Wacker WP 1235A has a mass of only 60kg. These lighter plates may be suitable for compacting laying course (all of 40mm deep) and doing the final consolidation/jointing of the blocks, but for sub-base compaction, they are way too light.
Incidentally, for Category I and II pavements (public highways) a plate of not less than 200kg mass is required.
In some parts of England, notably that London and beyond, the term 'scalpings' is used to refer to almost any crushed stone. Given that Praesepe was sold "Type 1 Scalpings" I'd guess that it is genuine DTp1, otherwise why use the term "Type 1", but the BM has put scalpings rather than simply "stone". There is no such thing as Type scalpings - there is scalpings, and there is Type 1, but the two are sort of mutually exclusive.
The methodology outlines is OK except for one point - the use of a "medium weight plate compactor". I know this is something else I've rattled on about previously, but according the the BS, the *minimum* plate mass for compaction of sub-base material on a category IV pavement (a driveway or patio) is 80kg. The vast majority of contractors, and nearly all DIYers end up using a plate of maybe half that mass, which is why we see so much settlement on completed driveways.
Whenever possible, a vibrating roller should be used to compact the sub-base. If you're lucky enough to own or have access to an 80kg plate, all well and good, but even one of the most popular plates, the Wacker WP 1235A has a mass of only 60kg. These lighter plates may be suitable for compacting laying course (all of 40mm deep) and doing the final consolidation/jointing of the blocks, but for sub-base compaction, they are way too light.
Incidentally, for Category I and II pavements (public highways) a plate of not less than 200kg mass is required.
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Here's their website http://www.sehmis.co.uk/our-branchesPraesepe wrote:.........I bought Type 1 scalpings according to the invoice from SEHMI
Seems a reptuable company to me
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